Bi-stable relay circuit



, .Im-19, 195o C. W. STIDGER BI-STABLE RELAY CIRCUAIT Filed July 30.1956 Arramffs" United States Patent C 2,922,086 'BI-STABLE RELAY CIRCUITClifford W. Stidger, San Lorenzo, Calif., assignor to Gerber ProductsCompany, Fremont, Mich., a corporation of Michigan Application July 30,1956, Serial No. 600,914

, 1 Claim. (Cl. 317-151) This invention relates to a means forestablishing a pulse controlled bi-stable relay to alternately shiftbetween one of two stable states.

In the past without using electronic control means to convert a pulseinput to operate a two stage counter so that each pulse constructedrelays with rotating armatures mechanical latch mechanisms andthe like.

A principal object of this invention is to provide a single relay ofconventional design with a novel resistance capacitance circuit toenable the relay to pickup and re- Other objects of the presentinvention will become apparent upon reading the following specificationand referring to the accompanying drawing in which similar characters ofreference represent corresponding parts in each of the several views.

' In the drawings:

The single figure is a schematic view of the preferred embodiment of theinvention.

Referring now to the drawing there is shown a relay A of conventionaldesign having a solenoid 13 which operates two or more sets of springreturn transfer points 14. The armature 15 of one set of points 14 isarranged to engage a contact 17 when the solenoid is unenergized andvengage a Contact 16 when energized. It is common in such relays that thesolenoids require current of at least a predetermined value to causetheir contacts to transfer to picked up condition, but aftertransferring current of substantially less value will hold the armaturein the picked up condition.

In this invention means are provided to regulate the current values tocause the relay armature to pickup, hold and drop out in response to apulse input. For convenience the current Value necessary to pickup thearmature will be hereinafter referred to as pickup current and thecurrent value necessary to hold the armature, but insufficient to pickupthe armature, will be referred to as holding current. Current valuebelow holding current is i referred to as drop out current.

A source of direct current B of a predetermined voltage is supplied forrelay A from a positive terminal 21 and negative terminal 22. Thesolenoid is connected through a resistor 23 to terminal 21 and through aresistor 24 to terminal 22. The resistance values of resistors 23 and l2,922,086 ce Patented Jan. 19, 1960 24 and solenoid 13 are selected toprovide bias current through the solenoid at the holding value. Resistor24 is of substantially lower value than resistor 23 and' is bypassed bya condenser 25, of relatively high value, in the range of 5 mfd. orbetter, so the circuit will allow a greater voltage swing when subjectedto changing current to assist in bringing current through the solenoidto the pickup value when a momentary pulse of pickup current is appliedthrough solenoid 13. Resistor 23 is suiciently high so when thepotential is first applied, although current through resistor 24 willmomentarily be bypassed through condenser 25, the relay armature 15 willnot pickup.

The positive side of solenoid a spring urged open push button circuitbreaker 26 to armature 15 and through a high capacity value condenser27, preferably at least l 13 is connected through control switch and maybe manually actuated or remotely controlled by a control relay (notshown).

Contact 17 is connected through a resistance 28 to the positive terminal21 and contact 16 is connected through g al resistance 29 to negativeterminal 22. By this arrangement when therelay armature 15 is droppedout condenser 27 is charged through resistance 28. While relay A is indropped out condition and when switch 26 is closed the condenser 27 thendischarges through solenoid 13 to bring the current up to pickup valuewhich causes relay A to pickup. When armature 15 is picked up condenser27 is discharged or bled olf through resistor 29. Resistance 29 is ofhigh enough value so while armature mentarily offers low enoug noid andbring the solenoid current down to drop out value.

In operation when the electrical power source B is first connected toterminals 21 and 22 the armature -15 remains in dropped out positionbecause the instantaneous current represented by the voltage supply Bacross the series network resistor 23 and solenoid 13 remains less thanthe pickup current. l

While armature 15 is in drop out position condenser 27 is charged topower Source B potential through resistance 28. When circuit breaker 26is momentarily closed there is an immediate discharge of condenser 27 tosend additional current through circuit breaker 26 to solenoid 13 tocomplement with the holding or bias current current through solenoid 13to the pickup current value. The sudden change of current is also seenby condenser 25 which permits a greater voltage swing to assure a pulseof suicient current to pickup armature 15.

cient to keep the relay current to below pickup value and the condenser27 at the solenoid potential while circuit breaker 26 is closed. Thenwhen circuit breaker 26 is opened condenser 27 is charged to supply Bpotential through resistance 28.

It can thus beseenthat repetitive opening and closure of circuit breaker26 will cause armature 15 to oscillate between the pickup and dropoutposition.

It has been found in one: particular relay having 1600 Y ohms DSC.solenoid resistance 20 ma. pickup current was required and 6 ma. holdingcurrent. With this relay, for example, it was ,found that a power sourceBof 125' volts, resistors 23, 28 and 29' of 10,000 ohms each, resistorZflcf 2,000 ohms, condenser 27' y1 nfd. and condenser 2S,- 20 mfd. was asatisfactoryl combination of relative values for the component parts.yWith this combination of values with switch 26 open there isapproximately 10 ma. bias current across solenoid `13. when switch Z6 isclosed while the relay is inV dropped out conditionL there issubstantially more Vthan 20l'rna'. across solenoid 1.3"fr'om dischargeof condenser 27 which causes' the relay to pickup. Then after thedischarge of condenser 27 the current-drops to ma. When switch 26 isthen open the currentfalls to 10ma. andiwhen again'close'dthere'is amomentary shunt 'across the solenoid 13 through condenser 27 which dropsthe current below 6 ma.Y so the relay drops out'. Then after the relaydrops out the current rises to about 8 or 9 ma. until the switch 27 isagain open wherein the current raises to 10 ma.

Many transfer points 14 may be employed in mechanically latchedrelationship withv relay A. Eachv relay transferpoint 1.*4'may be usedto directly operate motors, generators, electronic equipment and thelike. An example of vone application of theV invention is'in aninstallation where it is desired to have a push button switch arrangedto operate ay motor so that when the switchvis'pushed the motor lwillstart and when pushed again will stop and so on repetitively. Anotherapplication Where the device is useful is in combination with electroniccontrol devices having a pulse output whichcan close switch 26bysolenoid control. f

While therehas'been described a preferred embodiment of the invention,it is understood that certainemodiiications and changes may be practicedas limited only by the scope of the appended claim.

It isV claimed:

In combination a relay of the type having transfer pointsY including asolenoid actuated larmatureV alternatively engageable with first andsecond contact points; said armai ture spring urged in a rst position incontact with the first contact point andmovable to a second position `incontact with the second contact point when the solenoid of the relay isenergized by current above a flirst value and operable to maintain thesecond position until the current through the solenoid drops below asecond value which is less than the first current value; biasing meansVto energize said relay with current above said second value and belowsaid stval'uefsaid biasingm'eansincluding a first resistance element-serially connected between one input terminal of'the solenoid of therelay and-a iirstv terminal of a power source for 'the relay; a secondresistance' element serially connectedto a second terminal of thesolenoid of'the relay arid to a second terminal of the power source forthe relay;v and relay controll means to raise the current through thesolenoid of the relay above said iirst value and to lower the currentthrough thev solenoid of the relay belowY said second value;rsaidtrelaycontrol means including said transfer points, a condenser, a vthirdresist- Y ance means, 'a' fourth resistance means and a circuit breaker;said circuit breaker connecting said condenser serially with the secondterminal of the power source and the Vfirst 'terminalfof the solenoid ofthe relay when the circuit breaker is in the closed condition ofoperation; said' third resistance means connected to the first terminalof said power source and the iirst contact point of saidtransfertpoints; said fourth resistance means connected to the secondterminal of said power source andthe second contact point of said relaytransfer point; said' armature of said relay transfer lpoints connectedto saidcircuit breaker and said condenser to connect said thirdresistance means'to said condenser when said armatur'eis in the iirstposition of operation to charge said condenser through said thirdresistance means and to connect r`saidjfourth resistance means acrosssaid condenser to` 'discharge said condenserwhen said armature is in'thesecond'posit'ion of operation.

References Cited in the file of this patent UNITED STATES PATENTS-Lorenz Sept. 25, 1956 2,788,473 Breckman Apr. 9, 1957

